Lafarge’s Iligan preheater debottlenecking project

1 Introduction

Lafarge Iligan Cement is located on the North shore of Mindanao Island, Philippines, about 10 km from Iligan City. The cement plant has a dry process with a capacity of 1400 t/d clinker. The existing four stage SP type of preheating system is quite old and needed an up-grade to reach the new planned clinker output of 1600 t/d. The preheater system consists of a double string for C2 and C4 and a single string for C1 and C3.

Nanjing Kisen International Engineering Co., Ltd. signed the contract on 01.06.2013 to undertake the work related to the debottlenecking project on a turnkey basis including engineering, equipment supply, delivery, demolition works, erection and installation work, start up, commissioning as well as technical services.

2 Scope of work

Installation of a new down comer duct attached to the existing preheater building

Replacing of C4a and C4b (top cyclones) by new design cyclones including dip tubes and refractory

Modifying the existing C1 cyclone roof (bottom cyclone) to install a new dip tube

Installation of a new fresh air valve at the top of preheater building

Replacing the existing ID-fan by a new one and changing the motor on the same foundation

Installation of a new spray system (air atomizing) for GCT

Installation of a new compressor with air tank

All deconstruction work and modifying work was required by the existing equipment

Most important was to schedule the kiln shutdown period for the project to a tightly limited time of four weeks maximum. Engineering included Chinese standards, Lafarge safety rules and Lafarge technical standards and specifications.

3 Implementation of the contract

Nanjing Kisen arranged the work carefully and made good preparations for the project. The conversion was divided into two portions:

Number 1 was the work which could be finished before the kiln shutdown such as all the preparation work on site (Fig. 1), delivery of related equipment and materials (Fig. 2), as well as some deconstruction work (Fig. 3).

Number 2 was to be done during the kiln shutdown period, such as the ID-fan reinstallation etc. Detailed modifications were the following:

Down comer duct

The new down comer duct was installed with its supporting structure outside of the existing preheater building (Fig. 4). The individual ducts of C4a and C4b were combined into one down comer duct to lead the hot gases into new ID-fan inlet. The down comer duct was supported on the top of the compressor room. The entire down comer duct had to be designed according to a heat expansion of max. 500 °C and had to be insulated to minimize heat loss of the duct and for safety reasons (Tab. 1).

C4a and C4b top cyclones

The existing C4a and C4b top cyclones including the dip tubes (Fig. 5) were replaced by new cyclones plus dip tubes to achieve a lower pressure drop and higher dust collection efficiency (Fig. 6). The design of the new cyclones plus the dip tubes was based on the existing layout and duct arrangement. The existing concrete support of C4a, C4b had to be replaced by a steel support structure to reduce the load on the existing structure.

C1 cyclone

The existing C1 cyclone (bottom cyclone) was modified by replacing a new dip tube in order to achieve lower pressure drop and higher dust collection efficiency. The existing cyclone casing remained and was reused without modification except the connection parts with the new dip tube.

ID-fan

A new ID-fan was installed due to the incapability of the old existing fan (Fig. 7) capacity on pressure with the new clinker capacity of 1600 t/d. The new fan with a new motor was installed on the existing fan foundation in order to minimize the civil engineering works and the plant shutdown period for the replacing work. The new ID-fan (Fig. 8) is controlled by VSD and damper (Tab. 2).

GCT water spray system

Also installed was a new water spray system (air atomizing) to control the gas temperature at the outlet of the GCT. The water injection system was designed for all operating conditions, so that the temperature of the gases entering the ESP could be controlled accurately (Tab. 3). A new compressor with air tank was installed for the new spray system. The unit consists of the main pump unit with a back-up pump as well as valves and pipes for connection to the existing water tank.

4 Results

With strong support from the project team and hard work by Nanjing Kisen, the key target had been reached. The kiln shutdown time was only 22 days and afterwards the kiln capacity reached 1600 t/d. Thus, it turned out to be a successful project with a low investment budget, allowing full use of the production line of the existing facility.